Trail grooming device

ABSTRACT

Snow density in snow-vehicle, toboggan, or ski trails is increased by hurling snow displaced by the left and right quadrants of an arcuate snow shear toward each other to cause a violent collision and cause many of the snow particles to cohere. Apparatus to perform this action includes a long beam located along the axis of the groomer. Oppositely positioned side rails, held by struts extending from the beam, are joined by spring steel shears, preferably semi-circular, pivoted on each side rail. The device is effective when towed at speeds of from 3 - 25 miles an hour.

nited States Patent 1191 Cheney Aug. 20, 1974 TRAIL GROOMING DEVICE [76] Inventor: Stanley 0. Cheney, West Springfield, NH.

221 Filed: July 5,1972

21 Appl. No.: 269,077

[52] US. Cl 37/48, 404/96, 172/142,

172/188, 172/197, 172/652, 172/767, 172/787 [51] Int. Cl E0111 5/00 [58] Field of Search 172/612, 200, 767, 744,

[56] References Cited UNITED STATES PATENTS 146,848 l/l874 Thurston 172/701 235,431 12/1880 I-Iarter 172/197 791,726 6/1905 Schutte..... 404/118 X 945,787 1/1910 Krajeck 37/41 979,047 12/1910 Swagerty et a1. 172/387 X 1,011,230 12/1911 Moore 172/767 X l,l6l,275 11 1915 Wood 37 41 2,101,567 12/1937 Winsor 172/393 2,786,283 3/1957 Bradley 37/50 X 3,276,153 10/1966 Sorensen. 172/387 3,666,020 5/1972 Hess 37/41 FOREIGN PATENTS OR APPLICATIONS 110,020 3/1940 Australia 172/705 679,693 4/1930 France 172/652 678,804 4/1930 France 172/652 Primary Examiner-4. Reed Fisher Assistant Examiner-Eugene H. Eickholt Attorney, Agent, or Firm-Schiller & Pandiscio [5 7] ABSTRACT Snow density in snow-vehicle, toboggan, or ski trails is increased by hurling snow displaced by the left and right quadrants of an arcuate snow shear toward each other to cause a violent collision and cause many of the snow particles to cohere. Apparatus to perform this action includes along beam located along the axis of the groomer. Oppositely positioned side rails, held by struts extending from the beam, are joined by spring steel shears, preferably semi-circular, pivoted on each side rail. The device is effective when towed at speeds of from 3 25 miles an hour.

20 Claims, 3 Drawing Figures TRAIL GROOMING DEVICE I This invention relates to a trail-grooming device.

Trail grooming is a necessary operation if a skiing, snow-vehicle, or toboggan trail is to be used by numbers of persons in a recreation area. For various reasons, hard and soft places develop in a trail, and uneven wear on these unequal densities of snow causes bumps and lumps in the trail which are known as moguls. There are even weather conditions which will produce moguls naturally and where the surface of the snow becomes extremely bumpy. When these bumps are encountered by a motor sled or a toboggan, the continuing bumping and pounding becomes very disagreeable, and if the moguls are large, quite dangerous. It is somewhat worse on the ski trail, for some moguls can flip the skis of an experienced skier out of line and cause a spill. As a result, recreational areas which maintain trails for skiers, motorized snow vehicles, orchutes and runs for toboggans go to very considerable labor and expense to groom the trails and make them safe, comfortable, and fun to use.

The present device will groom a trail under usual snow conditions at speeds up to 25 miles an hour. Beyond this speed, if the trail is bumpy there may be a tendency for the groomer to become less effective. Not only does this device cut down and level the moguls and throw their substance into the hollows to leave a smooth trail, but it cuts down on excessive banking by throwing the snow from the bank back into the trail. All that is done by a device which weighs about 125 lbs., and is effective, depending on snow conditions, at towed speeds of from 3 to 25 miles an hour.

In the accompanying drawings:

FIG. 1 is a top plan view,

FIG. 2 is a vertical section through the assembly. The view shows the shears in an elevated position for clarity in illustration,

FIG. 3 is an elevation of the gage in position on the beam.

The trail groomer, 10, comprises a beam, 11, to the forward end of which a pilot ski, 12, is pivotally attached by the king pin, 13. The beam is suitably of any rigid shape which provides a flange which can dig into the snow and contribute lateral stability, such as, e.g., a channel or I-beam section. But for lightness, rigidity and strength, a shape having outreaching side flanges and an arched web is preferable. Such sections are frequently used as the supports for official highway signs. The high arch in the central portion of the beam not only forms a runner but gives excellent lateral stability.

at their inboard ends by the king pin, 13. The struts extend outwardly to left and right, are are joined to the respective side rails, 14 and 15, by pivot pins, 17-17.

The fit of the struts on the king pin, 13, and on pivot pins, 17-17, is sloppy so that it is possible to raise or lower the side rails above and below the plane of the central beam. This free or floating vertical motion should be at least plus or minus 1 inch. It is best if plus or minus 8 inches is provided, which allows the groomer to work on a wide variety of trail conditions. As an alternate to sloppy fit, other methods which permit vertical relative motion, e.g., hinges, can be used.

Near the ends of struts, 16-16, twists are made so that either a flat surface or one which is slanted upwardly very slightly is presented to the snow. The flat surface or the upward slant prevents the strut from diving under an icy crust as the groomer is being towed. The groomer is operative if the struts have other than a flat bar cross-section, but where the snow surface is icy, flat bars are much to be preferred.

Side rails, 14 and 15, are also joined by the bowed spring steel shears, l9 and .21, the ends of which are pivotally fastened to the respective side rails, 14 and 15, by the pivot pins, 18-18, with the result that the bowed shears may swing upwardly about their pivots.

The most effective form of shear is a semi-circle, but a semi-ellipse will operate with reduced efficiency. In the present example, each shear is formed from spring steel, one-half inch thick and 3 inches wide, curved to a diameter of 42 inches, pivoted at the ends of the semicircle.

The forward shear, 19, is primarily a cutting device. Shear, 21, the rear shear,,although exactly similar to shear, 19, does shear, but it also is an effective snow leveler. The springiness of the shears allows them actually to distort as the groomer is towed. If either shear hits an obstruction, the side rails, 14 and 15, pull toward each other to a small extent, and then spring outwardly as the obstruction is cleared.

Immediately before the shear reaches the pivot points, 18, the end portion is straightened so that it will lie parallel to and in contact with the side rails, 14 and 15. It is recommended that this parallel portion, 19a and 21a, extend forwardly from the pivot approximately 2/3 the height of the shear. Preferably also the ends of each shear are flat surfaces at right angles to the face of the shear. This slight extension is a significant aid in gathering snow.

When moving the groomer to the trail, or when returning after the trail has been groomed, the shears, 19 and 21, are flopped over to a forward and elevated position. The extreme outboard ends of the struts, 1616, are bent at a right angle to support the shear, 19, in this non-working position. Shear, 21, is supported in its non-working position by small stops, 20, fastened to the side rails, 14 and 15.

When the shears, l9 and 21, are semi-circular, which is the preferred configuration, the fixed or so-called mogul shear, 22, is rigidly fastened at right angles to the beam, 11, preferably at a distance equaling l/3 of the length of beam, measured from the king pin, and in such a position that it follows the line of a tangent to the shear circle. The mogul shear, 22, is formed from an angle bar and is fastened to beam, 11, with one arm, 23, lying parallel to the snow surface. The other arm, 24, projects downwardly. lts lower edge is relieved or chamfered to form a cutting edge, 25. Since the edge, 25, is subjected to considerable wear, a preferable construction is to make the downwardly projecting arm, 24, in two parts with a cutting edge portion, 26, made as a bolted-on, replaceable blade. The length of mogul shear, 22, is desirably at least 12 inches, but it may extend for 18 inches, or even longer, depending upon the condition of the snow. When the snow is other than hard packed, the longer lengths of mogul shears are used.

With the exception of the mogul shear, 22, all the parts fit together with movable or pivoted joints. It is thus possible for the trail groomer to ride around the outside of a curve, i.e., with the outside margin of the said rail, 14, elevated considerably above the plane of the opposite member, 15.

When it is desirable to lessen the depth of cut, a gage, 27, shown in elevation in FIG. 3 is bolted to the beam, 11. The series of holes, 28, in the beam, 11, allows the gage to be moved forward or set back, raising or lowering the shear, 19, to various heights above the beam. It is thus possible to prevent the shear from cutting too deep or attempting to move too much snow. A series of light cuts when the trail is very bumpy is the better practice, and will bring the trail into good condition much more quickly than if deep cuts are attempted.

The groomer is towed by a chain bridle, 29, fastened to the pilot ski, 12, so as to pull from both sides of the ski; e.g. fastened to a hitchplate, 31, or alternative hitching means. A pole hitch can be used if it is arranged to pull in substantially the same manner as the chain bridle, but it must be provided with a swivel to allow the groomer to tilt laterally, independently of the towing vehicle. The chain bridle, 29, is attached to the ski as low as possible, and preferably just before the toe of the pilot ski, l2, begins to rise.

If a tow bar is used, the end attached to the groomer should be bifurcated and attached to the ski on the hitch-plate, 31. To prevent the groomer from swinging too far out of line, the distance between the pulling vehicle and the groomer preferably should not exceed the width of the cut, e.g., 42 inches.

OPERATION The groomer is attached to the towing vehicle by passing the bridle through the pintle or behind the towing shackle. The great variation in snow conditions causes wide variations in the horse power which may be required. A l2-horse power track-type snow vehicle will pull the groomer through a wide variety of snow conditions, but if the trail have steep hills, or if the snow density be very heavy, or combinations of both exist, higher horse power towing vehicles will be required.

Normally both shears work with their lower edges resting on the beam. The arched web of the beam, 11, bites into the snow and gives lateral stability, while the long beam (usually about l feet long) prevents the two shears from quickly bobbing up and down or wallowing. ln effect, it establishes an average base line for the cut which is stably maintained because the beam resists side drifting. If, however, one side of the trail is steeply banked, that side of the groomer may rise since the struts, 16-16, are not rigidly fixed to the side rail, and a partial cutting down of the bank will take place, leaving a smooth banked turn.

The snow in the center of the groomer path is continuously cut down by the mogul shear, 22. This is prevented from jumping by a very substantial downpressure which is continuously exerted on the blade of shear, 22, by the long cantilever portion of beam, 11, which extends to the rear.

I explain the effect on the snow particles by the following: the snow in the right and left quadrants of the shear not only is moved at the forward velocity of the grooming device, but picks up a radial velocity due to the curved shape of the groomer blade. The result is, e.g., that all the snow in the right quadrant meets in a collision zone all the snow in the left quadrant at velocities which are always in excess of the forward velocity of the grooming device. On a straight trail, the colliding snow particles form a fountain which rises above the axis of the groomer some 3 5 feet, if the groomer is towed at about 15 miles per hour. An examination of the snow particles after the passage of the groomer shows that the snow has been distinctly modified. Many particles are considerably larger and pack much better than particles in an ungroomed snow-fall.

I explain this modification by the fact that the energy of collision is sufficient momentarily to heat the parti cles and cause the appearance of a surface liquid film. Immediately after these particles hit each other, their energy falls and particles return to an all-over frozen state in which it will be found that many of the particles are aggregated and have formed larger units.

Snow and atmospheric conditions are so variable that l have been unable to determine a critical speed at which this effect takes place. I have noted that the change occurs at towing speeds of from 3 15 miles an hour and above. Maximum consolidation occurs at the lower towing speeds in snows which are damp or wet, and air which is cold. Consolidation occurs in any event when the speed approaches 15 miles an hour, and temperatures are below freezing. But whether the above theory is the true explanation or not, I note as a fact that after the passage of a groomer equipped with arcuate blades and towed at speeds of between 3 and 15 miles an hour, the trail packs more easily and withstands considerably more wear than does snow which has not been so treated.

I claim:

1. A trail grooming device comprising a. a central beam,

b. a pilot ski pivotally attached to the forward end of said beam,

c. side rails located on either side of the beam,

d. struts pivotally connected to said ski and said side rails,

e. a curved cutting shear and a curved leveling shear each having opposite ends pivotally fastened to the respective side rails and having lower margins normally resting on the beam, and

f. means associated with the pilot ski to attach the device to towing means.

2. A trail grooming device according to claim 1 wherein said shears are semi-circular arcs of spring metal, and further wherein a short transverse shear is rigidly attached to the lower surface of the said beam in a position substantially tangent to said cutting shear.

3. A trail grooming device according to claim 1 wherein stops located in advance of the shear pivots are positioned on said side rails to support the said curved shears in a forwardly directed, inactive position while the said groomer is being moved to and away from the working area.

4. A trail grooming device according to claim 1 wherein each of the opposite ends of each of the said curved shears terminates in a straight portion lying parallel to the said side rails, and the ends of said shears are pivotally connected to said rails closely adjacent to the line where their curved and straight portions meet, and further wherein said straight portion of each shear extends beyond the pivot point a distance equal to substantially 2/3 of the height of the shears.

5. A trail grooming device according to claim 1 wherein the said curved shears and said struts are connected to the beam and side rails by loose fits to permit vertical movement of the said rails above and below the plane of the said beam.

6. A trail grooming device according to claim 2 wherein the said transverse shear is fastened to the beam at approximately l/3 of the length of thebeam from the pivot point of said ski, whereby, when the device is being towed, the cantilevered remaining portion of the beam exerts down-pressure on said transverse shear.

7. The method of increasing the density of the snow along ski and over-the-snow vehicle trails which includes providing a snow shear bent into semi-circular shape and towing the said shear with its concavity directed toward the direction of motion at speeds in excess of 3 miles an hour over a snow surface to impart to the displaced snow not only the forward velocity of the shear, but also a velocity which throws the snow from the right and left quadrants of the shear into a collision zone rising adjacent to and above the central radius of said shear, and allowing the snow with its density thereby increased to fall back onto the trail.

8. A trail grooming device comprising:

an elongated beam,

a ski member,

means for pivotally attaching said ski member to one end of said beam,

a pair of rail members disposed on opposite sides of said elongated beam,

strut means pivotally connected to each of said rail members and to said beam,

a first curved shear member extending between and pivotally connected to said rail members,

a second curved shear member extending and pivotally connected to said rail members,

said first and second shear members extending over said beam and spaced from one another longitudinally of said beam, and

means for coupling said device to towing means.

9. A device according to claim 8 wherein said curved shear members are made of spring metal.

10. A device according to claim 8 wherein said curved shear members are circularly curved.

11. A device according to claim 8 wherein the pivot axis of said beam relative to said strut means extends at an angle of approximately to the pivot axes of said first and second curved shear members relative to said rail members. 9

12. A device according to claim 11 wherein the pivot axis of said ski member relative to said beam extends at an angle of 90 to the pivot axes of said first and second curved shear members.

13. A device according to claim 12wherein the pivot axes of said rail members relative to said strutmeans extend at an angle of 90 relative to the pivot axis of said strut means relative to said beam.

14. A device according to claim 8 further including an elongate shear member affixed to and extending transversely of said beam, said shear member having a cutting edge located beneath said beam.

15. A device according to claim 14 wherein said elongate shear member is straight.

16. A device according to claim 15 wherein said elongate shear member extends substantially tangentially to one of said curved shear members.

17. A device according to claim 14 wherein at least a portion of said elongate shear member is located between said first and second curved shear members.

18. A device according to claim 8 further including stop means on said rail members for limiting the pivotal movement of said curved shear members relative to said rail members.

19. A device according to claim 8 further including means for varying the angle of at least one of said curved shear members with respect to said elongated beam.

20. A device according to claim 19 wherein said means for varying the angle of said one curved shear member includes a gage, said gage being movable along said elongated beam. 

1. A trail grooming device comprising a. a central beam, b. a pilot ski pivotally attached to the forward end of said beam, c. side rails located on either side of the beam, d. struts pivotally connected to said ski and said side rails, e. a curved cutting shear and a curved leveling shear each having opposite ends pivotally fastened to the respective side rails and having lower margins normally resting on the beam, and f. means associated with the pilot ski to attach the device to towing means.
 2. A trail grooming device according to claim 1 wherein said shears are semi-circular arcs of spring metal, and further wherein a short transverse shear is rigidly attached to the lower surface of the said beam in a position substantially tangent to said cutting shear.
 3. A trail grooming device according to claim 1 wherein stops located in advance of the shear pivots are positioned on said side rails to support the said curved shears in a forwardly directed, inactive position while the said groomer is being moved to and away from the working area.
 4. A trail grooming device according to claim 1 wherein each of the opposite ends of each of the said curved shears terminates in a straight portion lying parallel to the said side rails, and the ends of said shears are pivotally connected to said rails closely adjacent to the line where their curved and straight portions meet, and further wherein said straight portion of each shear extends beyond the pivot point a distance equal to substantially 2/3 of the height of the shears.
 5. A trail grooming device according to claim 1 wherein the said curved shears and said struts are connected to the beam and side rails by loose fits to permit vertical movement of the said rails above and below the plane of the said beam.
 6. A trail grooming device according to claim 2 wherein the said transverse shear is fastened to the beam at approximately 1/3 of the length of the beam from the pivot point of said ski, whereby, when the device is being towed, the cantilevered remaining portion of the beam exerts down-pressure on said transverse shear.
 7. The method of increasing the density of the snow along ski and over-the-snow vehicle trails whIch includes providing a snow shear bent into semi-circular shape and towing the said shear with its concavity directed toward the direction of motion at speeds in excess of 3 miles an hour over a snow surface to impart to the displaced snow not only the forward velocity of the shear, but also a velocity which throws the snow from the right and left quadrants of the shear into a collision zone rising adjacent to and above the central radius of said shear, and allowing the snow with its density thereby increased to fall back onto the trail.
 8. A trail grooming device comprising: an elongated beam, a ski member, means for pivotally attaching said ski member to one end of said beam, a pair of rail members disposed on opposite sides of said elongated beam, strut means pivotally connected to each of said rail members and to said beam, a first curved shear member extending between and pivotally connected to said rail members, a second curved shear member extending and pivotally connected to said rail members, said first and second shear members extending over said beam and spaced from one another longitudinally of said beam, and means for coupling said device to towing means.
 9. A device according to claim 8 wherein said curved shear members are made of spring metal.
 10. A device according to claim 8 wherein said curved shear members are circularly curved.
 11. A device according to claim 8 wherein the pivot axis of said beam relative to said strut means extends at an angle of approximately 90* to the pivot axes of said first and second curved shear members relative to said rail members.
 12. A device according to claim 11 wherein the pivot axis of said ski member relative to said beam extends at an angle of 90* to the pivot axes of said first and second curved shear members.
 13. A device according to claim 12 wherein the pivot axes of said rail members relative to said strut means extend at an angle of 90* relative to the pivot axis of said strut means relative to said beam.
 14. A device according to claim 8 further including an elongate shear member affixed to and extending transversely of said beam, said shear member having a cutting edge located beneath said beam.
 15. A device according to claim 14 wherein said elongate shear member is straight.
 16. A device according to claim 15 wherein said elongate shear member extends substantially tangentially to one of said curved shear members.
 17. A device according to claim 14 wherein at least a portion of said elongate shear member is located between said first and second curved shear members.
 18. A device according to claim 8 further including stop means on said rail members for limiting the pivotal movement of said curved shear members relative to said rail members.
 19. A device according to claim 8 further including means for varying the angle of at least one of said curved shear members with respect to said elongated beam.
 20. A device according to claim 19 wherein said means for varying the angle of said one curved shear member includes a gage, said gage being movable along said elongated beam. 